The application is directed toward a clutch disc contact improver for a differential.
The locking differential illustrated and claimed in U.S. Pat. No. Re. 28,004 has achieved significant commercial success. This differential retards relative rotation between the driven axles only when one axle achieves a rotational characteristic which exceeds the rotational characteristic of the other axle. This differs significantly from limited slip differentials wherein force is transmitted between the two axles constantly during all modes of operation. In both the locking differential and the limited slip differential, a plurality of clutch discs are employed to retard rotation between the axles during actuation of the respective differential. Although these clutch discs are manufactured in a manner entirely acceptable for operation of the respective differentials, applicant has determined that the close tolerances needed to achieve such satisfactory results can be loosened. It is to this concept which the following invention is directed.
Generally, the invention covers a novel design of a clutch for use in either a limited slip differential or a locking differential wherein the clutch includes a plurality of discs with an annular central protrusion on a preferred contact circle of one of the surfaces to contact an adjacent flat surface and a pair of radially spaced annular protrusions on another surface to contact an adjacent flat surface. The surfaces containing the protrusions may be on the discs or portions of the differential. If the protrusions are on the discs, the protrusions may be located either on the same disc, on adjacent discs, or on spaced discs. It is only necessary that the given protrusions be so situated that they contact a given surface or protrusions on an adjacent disc. The plate thickness of the discs must be such that they be at least capable of acting as a Belleville washer with a very low rate while the sections must be sufficiently adequate to transmit the required forces without excessive deformation. Rigid discs may also be used.